Exact solutions of a flat cosmological model in BSTT

Abstract

We solve the cosmological equations for the bimetric scalar—tensor theory of gravitation (BSTT) for a flat model of the Friedmann type with the equation of state p = aε. In the initial stage of expansion, the energy density of the scalar field dominates over the energy density of matter. As a result, the behavior of the solution in this limit does not depend on a. For later stages of expansion of the Universe, the solution obtained goes to a special solution having the form of a power law function of time. In this case, the relative change in the gravitational scalar is proportional to the Hubble parameter. In the limit of large values for the parameter of the theory, only a simple solution with zero value of the constant of integration goes to the corresponding Friedmann solution of general relativity theory.